Fix XML error messages

Fixes #825

radicale/tests/test_base.py

@@ -1059,10 +1059,13 @@ class BaseRequestsMixIn:
     </prop>
     %s
 </sync-collection>""" % sync_token_xml)
-        if sync_token and status == 409:
+        xml = DefusedET.fromstring(answer)
+        if status in (403, 409):
+            assert xml.tag == xmlutils.make_clark("D:error")
+            assert sync_token and xml.find(
+                xmlutils.make_clark("D:valid-sync-token")) is not None
             return None, None
         assert status == 207
-        xml = DefusedET.fromstring(answer)
         assert xml.tag == xmlutils.make_clark("D:multistatus")
         sync_token = xml.find(xmlutils.make_clark("D:sync-token")).text.strip()
         assert sync_token

radicale/xmlutils.py

@@ -131,7 +131,7 @@ def make_href(base_prefix, href):
 def webdav_error(human_tag):
     """Generate XML error message."""
     root = ET.Element(make_clark("D:error"))
-    root.append(ET.Element(human_tag))
+    root.append(ET.Element(make_clark(human_tag)))
     return root